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21 Cards in this Set
- Front
- Back
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Normal heart rate is determined by the cardiac action potential that originates from the SA node cells.
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True
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Pacemaker cells are AV cells.
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False
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One of the determinate for the cell-cell conduction of cardiac action potential is the high electrical resistance of gap junctions.
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False
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Arrhythmia is produced by only the abnormality of generation of cardiac action potential.
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False
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The action potential of the SA node has 5 phases.
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False
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A rapid Na inward current is cardiac ventricular cells determines the upstroke of the action potential.
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True
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When Na channels are completely or largely inactivated, any stimuli cannot induce large Na currents to depolarize myocytes, which is called effective refractory period.
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True
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The E-C coupling of cardiac cells depends upon intracellular Na levels, and cardiac contractility can be reduced d/t abnormality of E-C coupling.
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False
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Which mechanism is another important determinant of action potential conductance between cardiac cells in add-on to low electrical resistance of gap junctions?
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Voltage difference between cells
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Which event determines phase 3 depolarization of the action potential in ventricular cells?
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Outward K current
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The time period from phase 0 to membrane potential of - 60 mV in phase 3 is the:
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Effective refractory period
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Cardiac cells are unable to produce _________ during the effective refractory period b/c Na channels are completely or largely inactivated.
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A new action potential
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The coupling of the action potential of the cell membrane to cardiac contraction depends of which ion movement?
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Ca released from SR
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Which stimuli activates baroreceptors during the baroreflex?
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Distention of vascular walls
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What indicates that the baroreflex is a negative feedback loop?
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Increased b/p causes vasodilation and bradycardia
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In response to decrease in blood volume, activation of renin-angiotensin II system and decrease in atrium natriuretic peptide results in:
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wrong answer-ask
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Ca channel blockers cannot be used for:
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Arrhythmia
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Increase in ____ leads to more blood pumping into the aorta and thereby increases systolic pressure.
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Stroke volume
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Abnormality of ______ reduces cardiac contractility and _______ is enhanced by drugs for treatment of heart failure:
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E-C coupling
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If _____ increases, diastolic arterial b/p is elevated primarily.
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Peripheral arterial resistance
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A larger ____ will expand the vessel more and thereby increase mean arterial blood pressure.
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Circulatory blood volume
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